This is a known issue that will occur if you copied a question by using the "Duplicate" button and tried to publish a survey in the web designer. The fix will be available as a hotfix to the website in the next week.

In the meantime, you can fix the error manually by using the new capability "Modify Schema" in our 2.5 release. Just change the second "field_1" to another name in the Modify Schema dialog will allow you publish the survey.